21236013493 has 2 divisors, whose sum is σ = 21236013494. Its totient is φ = 21236013492.

The previous prime is 21236013481. The next prime is 21236013521. The reversal of 21236013493 is 39431063212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20307105009 + 928908484 = 142503^2 + 30478^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21236013493 is a prime.

It is a super-2 number, since 2×21236013493² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21236013443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10618006746 + 10618006747.

It is an arithmetic number, because the mean of its divisors is an integer number (10618006747).

Almost surely, 2^21236013493 is an apocalyptic number.

It is an amenable number.

21236013493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21236013493 is an equidigital number, since it uses as much as digits as its factorization.

21236013493 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 34.

The spelling of 21236013493 in words is "twenty-one billion, two hundred thirty-six million, thirteen thousand, four hundred ninety-three".